Methanol-to-olefin processes are well described in the art. Typically, methanol-to-olefin processes are used to produce predominantly ethylene and propylene. An example of such a methanol-to-olefin process is described in WO-A 2006/020083. In the process of WO-A 2006/020083, the methanol is first converted into dimethylether (DME) prior to be subjected to a conversion to olefins, thereby reducing the amount of water produced during the conversion to olefins. Both methanol and DME are suitable feedstocks for a Methanol-to-olefin process and therefore such processes are also generally referred to as oxygenate-to-olefin (OTO) processes.
In EP2024303A1, another OTO process is described wherein in addition to oxygenates, also C4 olefins are provided to the OTO process. These C4 olefins are provided as an olefinic co-feed together with the oxygenates. By providing a C4 olefinic co-feed to the OTO process more ethylene and propylene may be produced. According to EP2024303A1, suitable sources for these C4 olefins are for instance C4 hydrocarbon fractions obtained from refinery units such as thermal cracking units, catalytic cracking units, steam cracking units, naphtha (steam) cracking units, butadiene extraction units. However, many of these stream are the primary source for butadiene, which is a base chemical or for instance the production of synthetic rubber materials and other polymers.
By providing the mentioned C4 hydrocarbon fractions to an OTO process, less butadiene is available, which may lead to a discrepancy between the butadiene demand and supply.